The disclosure relates to methods and apparatus for monitoring a plurality of worksites at a facility. One example of such a facility is an offshore facility for the production of petroleum, of the type referred to as “offshore rigs” or “offshore platforms.” It will be understood that an offshore facility can include floating vessels, semi-submerged vessels, submerged vessels, work barges, work boats, floating production systems (FPS), and need not be fixed relative to the earth. It will also be understood that other types of facilities located on dry land, such as petroleum refineries, chemical plants, large buildings to be renovated, remote pipelines, and mines, can be serviced with methods and apparatus of the disclosure. All types of worksites within such facilities can be serviced using methods and apparatus of the disclosure. These worksites can include worksites including one or more confined spaces. Examples of confined space worksites include, for example, the interior of a tank, a hull of a vessel, or a spar of an FPS. Generally, a “confined space” includes any worksite where egress by a worker from a potentially dangerous condition, or ingress by rescue personnel, is limited by a substantial restriction. Examples of restrictions are doorways, hatches, ladders, vertical distance, vertical exit hatches, crawl spaces, scaffolding, suspended platforms, walls, or any other condition which limits egress by a worker. It will be understood that “worksite,” although not limited to the following, includes locations where work at a facility tends to be temporary in nature, and frequently involves maintenance, repair, cleanup, demolition, renovation, or construction projects. Numerous such worksites can be operational at any one time in a large facility, such as a large offshore facility, such as when work crews are scattered about performing maintenance duties inside large tanks, spars, and similar structures. Frequently, the tanks contain residual flammable materials and flammable vapors, or materials in use by the crews are flammable materials or create flammable vapors. Likewise, tanks and confined spaces can include harmful gases such as carbon monoxide and H2S. In some situations, workers are situated in elevated or suspended positions inside confined, dark tanks having a single, distant access hatch. One way to monitor worker safety in such situations is to assign a “hole watcher” who is charged with standing outside the tank access hatch and periodically peering inside to determine if other workers located inside the tank are working normally, or if someone requires assistance from rescue personnel. Rescue can be difficult to effectuate, because numerous power cables and ventilation ducts may also enter the tank through the same access hatch, and due to confined space entries. If the “hole watcher” attempts to enter the tank and assist a worker in duress, the door looker can also be overcome by conditions such as hazardous gases, thus endangering the safety of all members of a work crew at the same worksite. If the “hole watcher” becomes distracted and fails to observe conditions and promptly notify rescue personnel to respond to dangerous conditions, catastrophic injuries and economic losses can result.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for improved methods and apparatus for monitoring a plurality of worksites.